We did this trip as a day trip from Bangkok 07.02.09. A taxi is 1.800 THB.
For White-faced Plover see David Bakewell and Peter Kennerley "Malaysia's Mystery Plover" at surfbirds. (http://www.surfbirds.com/Features/plovers1108/malayplovers.html)
Highly recommanded is the local guide Mr. Tee. Tel: 0810058974. 1.000 THB per day. We met Mr. Tee in Khok Kham near Samut Sakorn, had a Spoon-billed Sandpiper there and went to Laem Phak Bia near Petchaburi.
The areas Khok Kham and Laem Phak Bia are vast. So you need more than good luck to find the birds you want to see, unless you have a local guide.
Spoon-billed Sandpiper (1)
White-faced Plover (2)
Nordmann's Greenshank (15)
Chinese Egret (1)
Pied Advocat (12)
Malaysian Plover (4)
....